Gunman Kills 1, Wounds 2 at Phoenix Office Complex, Manhunt Under Way

Comstock/Thinkstock(PHOENIX) -- Police continue searching for a 70-year-old man who they believe shot three people at a Phoenix office, killing one man and leaving another in critical condition.

Police identified the suspect as Arthur Douglas Harmon, 70, of the Phoenix area, who, they said, opened fire around 10:30 a.m. local time after a meeting at the office building.

"We believe that there was some type of meeting concerning some pending litigation," Phoenix Police Sgt. Tommy Thompson told ABC News. "There was an altercation after the meeting had concluded. That is when Harmon shot the two people" wounded most seriously, as well as a 32-year-old woman who received less serious wounds.

A witness followed a Kia Optima, Arizona license plate AVS-2052, believed driven from the scene by Harmon, Thompson said, but stopped the pursuit when the car's occupant opened fire.

One of the two seriously wounded men in the office shooting later died. Police identified him as Steve Singer, 48.

In addition, a 43-year-old man was in critical condition Wednesday evening, Thompson said.

Police wouldn't identify the wounded man or woman, or describe the nature of the relationship between the suspect and the victims.

Police asked for the public's help locating Harmon, though Thompson noted, "We believe he is armed and dangerous."

In the immediate aftermath of the shooting, police cleared the office complex in the 7310 block of 16th Street, near Glendale Avenue.

Officials said there was only one gunman, who remained at large.

A witness told ABC News she heard several shots, and took cover in an IT closet with several other women. Another witness heard between six and 10 shots fired.

Police believe the suspect entered the building looking for a specific individual, but was confronted and an altercation ensued, Thompson told ABC News affiliate KNXV-TV.

In addition to the office complex and the suspect's home, police were also investigating a third scene, according to KNXV-TV. It was not clear how it was related to the office shooting.

The shooting took place moments after former Arizona Rep. Gabrielle Giffords, the victim of a shooting in Tucson, Ariz., in 2011, testified before Congress on gun control.

In the weeks since 20 students were gunned down at a Newtown, Conn., elementary school on Dec. 14, 2012, several mass shootings have garnered public attention as the nation debates its relationship to firearms.

Five days ago, two men were wounded during a shooting at Lone Star College in Houston. Earlier this month, a 16-year-old student was arrested after shooting a classmate in Taft, Calif.